Superchargers increase airflow to an engine that powers the supercharger. The increased airflow enables the engine to burn more fuel, which results in a commensurate increase in engine power. For example, a centrifugal supercharger uses a small impeller driven by the engine to draw air into the supercharger from a fill side, compress the air in a compression chamber, and feed compressed air into the engine's combustion chamber via a discharge side. On most conventional superchargers, the pressure at the fill side is typically fixed, and does not allow for variations to optimize volumetric and thermal efficiency for specific applications. Internal lubrication of gearing involving transfer of power from the engine to the impeller is often sub-optimal and can affect longevity.